1. Field of the Invention
The invention relates to a cooling fan, more particularly to a cooling fan that has a casing and a circuit board directly connected to a surrounding wall of the casing.
2. Description of the Related Art
Referring to FIGS. 1 and 2, a conventional cooling fan 1 is shown to include a casing 11, a control unit 12, a stator 13, a fan blade unit 14 and a pair of bearings 15.
The casing 11 has a surrounding wall 110, a mounting base 111 extending from the surrounding wall 110, and a hollow shaft 112 fixedly mounted on the mounting base 111.
The control unit 12 includes a circuit board 121 seated on a shoulder of the hollow shaft 112 and spaced apart from the mounting base 111, and a sensing component 122 provided on the circuit board 121.
The stator 13 is secured to and is connected electrically to the circuit board 121 of the control unit 12. The fan blade unit 14 is rotatable relative to the stator 13.
The fan blade unit 14 includes a hollow hub 141 that covers the stator 13, a rotating axle 142 disposed in the hollow hub 141 and journalled to the hollow shaft 112 of the casing 11, a plurality of blades 143 extending outwardly from the hollow hub 141, a magnetic ring 144 serving as a rotor and mounted on an inner face of the hollow hub 141.
The two bearings 15 are spaced apart from each other, and are mounted in the hollow shaft 112 of the casing 11. The rotating axle 142 is journalled to the hollow shaft 112 through the bearings 15.